This invention relates to a scroll saw, and more particularly to a so called walking beam scroll saw or jig saw.
Generally, a scroll saw utilizes two parallel arms or beams pivotally mounted on a frame and having a relatively thin blade under tension between the outer ends of the beams. The beams are pivotally mounted on trunnions which in turn are journaled in bearings carried by the frame of the scroll saw. At the opposite end of the beams, an adjustable bolt and spring is provided so as to maintain the blade under tension. A motor or other drive system is connected to one of the beams so as to reciprocate the beams in an up and down fashion on their trunnions such that the saw blade reciprocates in a generally vertical blade plane relative to the work piece for cutting purposes. Such scroll saws may be utilized to make both straight line and curvilinear cuts in rather intricate patterns and shapes in a variety of sheet like materials including wood, metal, plastics and the like. Generally, the teeth on the blade are so shaped such that the blade cuts only on the down stroke.
Such walking beam scroll saws are well known and reference may be made to my previous co-assigned U.S. Pat. No. 4,616,541. In addition, reference may be made to such U.S. Pat. Nos. as 76,730, 83,362, 126,740, 191,239, 2,240,307, 3,104,688, 3,213,909, and 3,878,876. In addition, French Patent No. 1,206,523 and British Patent No. 22,960 may also be of interest.
In scroll saws such as disclosed in my prior U.S. Pat. No. 4,616,541 and other similar prior art scroll saws, it has been a continuing and longstanding problem that, due to the fact that the pivot bearings for the trunnions of the upper and the lower beams or arms of the saw are somewhat out of alignment with one another, the ends of the beam are accordingly somewhat misaligned with respect to the plane of arm travel as the arms are reciprocated up and down. This means that the reciprocating motion of the blade may not be coincident with the direction in which the teeth of the blade are oriented. In turn, this may result in less efficient cutting action for the blade in an inaccurate cut, and binding between the blade and the workpiece.
Additionally, many such scroll saws are designed such that the work table is pivotally moveable with respect to the frame so as to permit bevel cuts in the work piece by inclining the work table and the work supported thereby relative to the vertical plane of the blade. However, such scroll saw designs have typically utilized a compression coil spring interposed between a support for table and the work table itself so as to minimize rattling of the table with respect to the support. These compression coil springs, however, worked effectively in only one plane, primarily in the longitudinal direction of the coil spring, and took up considerable room (volume) in the saw.